EP0741678B1 - Superconducting material and method for preparing superconducting materials - Google Patents

Superconducting material and method for preparing superconducting materials Download PDF

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Publication number
EP0741678B1
EP0741678B1 EP95907684A EP95907684A EP0741678B1 EP 0741678 B1 EP0741678 B1 EP 0741678B1 EP 95907684 A EP95907684 A EP 95907684A EP 95907684 A EP95907684 A EP 95907684A EP 0741678 B1 EP0741678 B1 EP 0741678B1
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temperature
precursor
silver
oxide
preparing
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French (fr)
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EP0741678A1 (en
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Miguel Angel Alario-Franco
Catherine Chaillout
Jean-Jacques Capponi
Jean-Louis Tholence
Bénédicte SOULETIE
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Nexans SA
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Alcatel CIT SA
Alcatel SA
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/45—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on copper oxide or solid solutions thereof with other oxides
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0268—Manufacture or treatment of devices comprising copper oxide
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/80—Constructional details
    • H10N60/85—Superconducting active materials
    • H10N60/855—Ceramic superconductors
    • H10N60/857—Ceramic superconductors comprising copper oxide
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/775—High tc, above 30 k, superconducting material
    • Y10S505/776—Containing transition metal oxide with rare earth or alkaline earth
    • Y10S505/779—Other rare earth, i.e. Sc,Y,Ce,Pr,Nd,Pm,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu and alkaline earth, i.e. Ca,Sr,Ba,Ra
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/775—High tc, above 30 k, superconducting material
    • Y10S505/785—Composition containing superconducting material and diverse nonsuperconducting material

Definitions

  • the present invention relates to superconductors of ceramic type with high critical temperature.
  • These materials are made in the form of ceramics by subjecting a mixture of precursors, in substantially proportion stoichiometric with excess oxygen, at temperatures and high pressures.
  • the present invention provides a superconductive material of the A-Ba-Ca-Cu-O family in which A is copper.
  • the present invention provides a process for manufacturing superconductive ceramics starting from a Ba-Ca-Cu-O type precursor, in substantially stoichiometric proportion for the formation of CuBa 2 Ca n-1 Cu n O x and silver oxide.
  • a superconductive ceramic is thus obtained comprising grains of compounds having the above-mentioned formula and metallic grains of silver.
  • silver atoms are present in the superconductive grains and contribute to obtaining the superconductive qualities of the compound which will be set out below.
  • the inventors prepared ceramic samples at high pressure (greater than 4 GPa) and high temperature (850 to 1000 ° C and preferably 900 to 950 ° C) using a belt type pressurizing device.
  • a precursor of nominal composition Ba 2 Ca n-1 Cu n + 1 O x or Ba 2 Ca n-1 Cu n O x was prepared as indicated in the article by Antipov et al., Physica C, 215, 1 (1993). More generally, this precursor can be obtained by mixing oxidized compounds in the form of powder such as oxides, nitrates or carbonates of barium, calcium and copper in the targeted proportions, this operation being carried out under an atmosphere of oxygen under pressure atmospheric at a temperature of 850 to 950 ° C for several hours.
  • the precursor obtained is hygroscopic and must be stored in an oxygen atmosphere or in a neutral atmosphere.
  • Silver oxide and the precursor (and possibly excess copper oxide) were finely ground and mixed before being arranged in the aforementioned synthesis system.
  • the pressure was first increased up to a value of around 5 GPa then the temperature was increased to the desired value in approximately one hour. After that, the temperature and pressure were maintained for more than an hour.
  • a ceramic block comprising grains of a size of the order of a hundred micrometers which were identified by X-ray diffraction as being made up of various phases of CuBa 2 Ca n-1 Cu n O x where n was between 1 and 6. It is nevertheless possible that there are also in the material obtained members of the family where n is greater than 6.
  • the block obtained also contained grains of silver or silver compounds less than 10 microns in size. We can therefore consider that silver essentially served as a catalyst for obtaining CuBa 2 Ca n-1 Cu n O x although it is not excluded that it remains in very small proportion in each of the ceramic grains. silver atoms possibly playing a role in the superconducting properties.
  • a structure is obtained substantially as described by SN Putilin et al. in Nature 362, 226 (1993) and EV Antipov et al. in Physica C, 215, 1 (1993) but where mercury is replaced by copper.
  • a compound was prepared according to the general indications above in which, more particularly, the phase of high pressure ceramic preparation was carried out under a pressure of 4 GPa (40 kbars) at a temperature of 850 ° C for an hour and a half.
  • the precursor was in the form of a finely ground powder of Ba 2 Ca 2 Cu 3 O x and one unit of precursor was mixed with two units of silver oxide AgO, also in the form of powder.
  • Magnetic susceptibility measurements performed on the body obtained are illustrated in Figure 1.
  • diamagnetism remains zero until appreciably 120 K, that a diamagnetism appears appreciably for 120 K and that the diamagnetism curve has lags at around 95 and 77 K.
  • the ceramic obtained contains three superconductive compounds respectively having critical temperatures of 120, 95 and 77 K.
  • the magnetic susceptibility curve, illustrated in figure 4 presents like that of figure 3 a transition marked at 120 K. Nevertheless, considering on a large scale more magnified this magnetic susceptibility, we note that a setback appears at a temperature of 275 K, that is to say + 2 ° C. Similar high-sensitivity experiments did not were performed for the samples in Figures 1, 2 and 3 and it it is not excluded that similar results also appear for these samples.
  • phase to which the material exhibiting corresponds this very high critical temperature has not been identified with precision but today we consider that it is a material for which the phase n is high (of the order of 6 or more).
  • this high value of the critical temperature may be due to the keeping of silver atoms inside of the superconducting phase.
  • the method according to the present invention makes it possible to obtain a superconductive compound whose main formula is CuBa 2 Ca n-1 Cu n O x but more generally, the present invention relates to any body obtained by the described method consisting in manufacturing a ceramic under high pressure and high temperature from a precursor or a mixture of precursors of Ba 2 Ca n-1 Cu n + 1 O x in the presence of silver to provide a superconductive material at high critical temperature.
  • This compound can comprise an excess of calcium and a barium defect according to the formula CuBa 2-y Ca n-1 + y Cu n O x where y is between 0 and 0.5.
  • composition of the precursor can be modified and is not necessarily strictly stoichiometric.
  • variable amounts of oxide may be provided silver, commonly in the range of one to three moles of oxide money for one mole of precursor.

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  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
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Description

La présente invention concerne les supraconducteurs de type céramique à température critique élevée.The present invention relates to superconductors of ceramic type with high critical temperature.

On connaít des supraconducteurs du système Ba-Ca-Cu-O tels que les familles ABa2Can-1CunOx où n est un entier supérieur à 1, x est supérieur à 2n+2, et A est du mercure ou du thallium. Ces matériaux présentent des températures critiques élevées, supérieures à 100 K pour certaines phases, c'est-à-dire certaines valeurs de n. Cette température critique augmente quand le matériau est utilisé à pression élevée. Pour le mercure et le thallium, il a été constaté que la température critique augmente à l'intérieur d'une famille donnée avec la valeur de n jusqu'à n=3 et diminue ensuite.We know superconductors of the Ba-Ca-Cu-O system such as the families ABa 2 Ca n-1 Cu n O x where n is an integer greater than 1, x is greater than 2n + 2, and A is mercury or thallium. These materials have high critical temperatures, greater than 100 K for certain phases, that is to say certain values of n. This critical temperature increases when the material is used at high pressure. For mercury and thallium, it has been found that the critical temperature increases within a given family with the value of n up to n = 3 and then decreases.

Ces matériaux sont fabriqués sous forme de céramiques en soumettant un mélange de précurseurs, en proportion sensiblement stoechiométrique avec un excès d'oxygène, à des températures et des pressions élevées. These materials are made in the form of ceramics by subjecting a mixture of precursors, in substantially proportion stoichiometric with excess oxygen, at temperatures and high pressures.

Nonobstant les propriétés très intéressantes présentées par les composés du type Hg-Ba-Ca-Cu-O et Tl-Ba-Ca-Cu-O, les recherches se poursuivent pour trouver d'autres céramiques supraconductrices à température critique élevée, d'une part dans l'espoir d'atteindre des températures critiques encore plus élevées, d'autre part dans le but d'éviter d'utiliser des corps fortement toxiques tels que le thallium et, à un degré moindre mais non négligeable, le mercure.Notwithstanding the very interesting properties presented by compounds of the Hg-Ba-Ca-Cu-O and Tl-Ba-Ca-Cu-O type, research continues to find other ceramics high critical temperature superconductors on the one hand in the hope of reaching even more critical temperatures on the other hand in order to avoid using bodies highly toxic such as thallium and, to a lesser degree but not negligible, mercury.

Ainsi, la présente invention prévoit un matériau supraconducteur de la famille A-Ba-Ca-Cu-O dans lequel A est du cuivre. D'autre part, la présente invention propose un procédé de fabrication de céramiques supraconductrices partant d'un précurseur de type Ba-Ca-Cu-O, en proportion sensiblement stoechiométrique pour la formation de CuBa2Can-1CunOx et d'oxyde d'argent. On obtient ainsi une céramique supraconductrice comprenant des grains de composés ayant la formule susvisée et des grains métalliques d'argent. Néanmoins, il n'est pas exclu dans l'état actuel des recherches que des atomes d'argent soient présents dans les grains supraconducteurs et contribuent à l'obtention des qualités supraconductrices du composé qui seront exposées ci-après.Thus, the present invention provides a superconductive material of the A-Ba-Ca-Cu-O family in which A is copper. On the other hand, the present invention provides a process for manufacturing superconductive ceramics starting from a Ba-Ca-Cu-O type precursor, in substantially stoichiometric proportion for the formation of CuBa 2 Ca n-1 Cu n O x and silver oxide. A superconductive ceramic is thus obtained comprising grains of compounds having the above-mentioned formula and metallic grains of silver. However, it is not excluded in the current state of research that silver atoms are present in the superconductive grains and contribute to obtaining the superconductive qualities of the compound which will be set out below.

Ces objets, caractéristiques et avantages ainsi que d'autres de la présente invention seront exposés en détail dans la description suivante de modes de réalisation particuliers faite en relation avec les figures 1 à 4 jointes qui représentent des courbes de susceptibilité magnétique en fonction de la température pour des corps obtenus par le procédé selon la présente invention.These objects, characteristics and advantages as well as others of the present invention will be detailed in the following description of particular embodiments made in connection with attached figures 1 to 4 which represent magnetic susceptibility curves as a function of the temperature for bodies obtained by the process according to the present invention.

Les inventeurs ont préparé des échantillons de céramique à haute pression (supérieure à 4 GPa) et haute température (850 à 1000°C et de préférence 900 à 950°C) en utilisant un appareil de mise sous pression de type belt. Un précurseur de composition nominale Ba2Can-1Cun+1Ox ou Ba2Can-1CunOx a été préparé de la façon indiquée dans l'article de Antipov et al., Physica C, 215, 1 (1993). Plus généralement, ce précurseur peut être obtenu en mélangeant des composés oxydés sous forme de poudre tels que des oxydes, des nitrates ou des carbonates de baryum, calcium et cuivre dans les proportions visées, cette opération étant réalisée sous une atmosphère d'oxygène à pression atmosphérique à une température de 850 à 950°C pendant plusieurs heures. Le précurseur obtenu est hygroscopique et doit être conservé en atmosphère d'oxygène ou en atmosphère neutre.The inventors prepared ceramic samples at high pressure (greater than 4 GPa) and high temperature (850 to 1000 ° C and preferably 900 to 950 ° C) using a belt type pressurizing device. A precursor of nominal composition Ba 2 Ca n-1 Cu n + 1 O x or Ba 2 Ca n-1 Cu n O x was prepared as indicated in the article by Antipov et al., Physica C, 215, 1 (1993). More generally, this precursor can be obtained by mixing oxidized compounds in the form of powder such as oxides, nitrates or carbonates of barium, calcium and copper in the targeted proportions, this operation being carried out under an atmosphere of oxygen under pressure atmospheric at a temperature of 850 to 950 ° C for several hours. The precursor obtained is hygroscopic and must be stored in an oxygen atmosphere or in a neutral atmosphere.

Parallèlement, on a synthétisé de l'oxyde d'argent, AgO ou Ag2O ou un mélange de ces oxydes.At the same time, silver oxide, AgO or Ag 2 O or a mixture of these oxides was synthesized.

L'oxyde d'argent et le précurseur (et éventuellement un excès d'oxyde de cuivre) ont été finement broyés et mélangés avant d'être disposés dans le système de synthèse susmentionné.Silver oxide and the precursor (and possibly excess copper oxide) were finely ground and mixed before being arranged in the aforementioned synthesis system.

Classiquement, la pression a d'abord été augmentée jusqu'à une valeur de l'ordre de 5 GPa puis la température a été augmentée jusqu'à la valeur désirée en sensiblement une heure. Après cela, la température et la pression ont été maintenues pendant plus d'une heure.Classically, the pressure was first increased up to a value of around 5 GPa then the temperature was increased to the desired value in approximately one hour. After that, the temperature and pressure were maintained for more than an hour.

Après mise à température et pression normale, on a obtenu un bloc de céramique comprenant des grains d'une dimension de l'ordre de la centaine de micromètres qui ont été identifiés par diffraction aux rayons X comme étant constitués de diverses phases de CuBa2Can-1CunOx où n était compris entre 1 et 6. Il est néanmoins possible qu'il existe également dans le matériau obtenu des membres de la famille où n est supérieur à 6. Le bloc obtenu contenait également des grains d'argent ou de composés d'argent d'une dimension inférieure à 10 micromètres. On peut donc considérer que l'argent a essentiellement servi de catalyseur pour l'obtention de CuBa2Can-1CunOx bien qu'il ne soit pas exclu qu'il demeure en très faible proportion dans chacun des grains de céramique des atomes d'argent jouant éventuellement un rôle dans les propriétés supraconductrices. En gros, indépendamment de la présence des grains d'argent, on obtient une structure sensiblement telle que décrite par S.N. Putilin et al. dans Nature 362, 226 (1993) et E.V. Antipov et al. dans Physica C, 215, 1 (1993) mais où le mercure est remplacé par du cuivre. After setting to normal temperature and pressure, a ceramic block was obtained comprising grains of a size of the order of a hundred micrometers which were identified by X-ray diffraction as being made up of various phases of CuBa 2 Ca n-1 Cu n O x where n was between 1 and 6. It is nevertheless possible that there are also in the material obtained members of the family where n is greater than 6. The block obtained also contained grains of silver or silver compounds less than 10 microns in size. We can therefore consider that silver essentially served as a catalyst for obtaining CuBa 2 Ca n-1 Cu n O x although it is not excluded that it remains in very small proportion in each of the ceramic grains. silver atoms possibly playing a role in the superconducting properties. Basically, independently of the presence of the silver grains, a structure is obtained substantially as described by SN Putilin et al. in Nature 362, 226 (1993) and EV Antipov et al. in Physica C, 215, 1 (1993) but where mercury is replaced by copper.

Exemple 1Example 1

On a préparé un composé selon les indications générales ci-dessus dans lequel, plus particulièrement, la phase de préparation de céramique à haute pression était réalisée sous une pression de 4 GPa (40 kbars) à une température de 850°C pendant une heure et demi.A compound was prepared according to the general indications above in which, more particularly, the phase of high pressure ceramic preparation was carried out under a pressure of 4 GPa (40 kbars) at a temperature of 850 ° C for an hour and a half.

Le précurseur était sous forme de poudre finement broyée de Ba2Ca2Cu3Ox et une unité de précurseur a été mélangée à deux unités d'oxyde d'argent AgO, également sous forme de poudre.The precursor was in the form of a finely ground powder of Ba 2 Ca 2 Cu 3 O x and one unit of precursor was mixed with two units of silver oxide AgO, also in the form of powder.

Les mesures de susceptibilité magnétiques effectuées sur le corps obtenu sont illustrées en figure 1. On obtient une susceptibilité magnétique XI' en unité électromagnétique (emu/g) telle qu'illustrée en figure 1. On voit que le diamagnétisme reste nul jusqu'à sensiblement 120 K, qu'un diamagnétisme apparaít sensiblement pour 120 K et que la courbe de diamagnétisme présente des décrochements à environ 95 et 77 K. Ceci indique que la céramique obtenue contient trois composés supraconducteurs ayant respectivement des températures critiques de 120, 95 et 77 K.Magnetic susceptibility measurements performed on the body obtained are illustrated in Figure 1. We obtain a magnetic susceptibility XI 'in electromagnetic unit (emu / g) as illustrated in figure 1. We see that diamagnetism remains zero until appreciably 120 K, that a diamagnetism appears appreciably for 120 K and that the diamagnetism curve has lags at around 95 and 77 K. This indicates that the ceramic obtained contains three superconductive compounds respectively having critical temperatures of 120, 95 and 77 K.

Bien que cela n'ait pas encore été prouvé de façon certaine, les inventeurs supposent que ces trois températures critiques correspondent à des composés pour lesquels les valeurs de n correspondent vraisemblablement à 3, 4, 5, ou 6.Although it has not yet been proven certain, the inventors assume that these three temperatures critical correspond to compounds for which the values of n probably correspond to 3, 4, 5, or 6.

Exemple 2Example 2

Dans les mêmes conditions de pression et de température que dans l'exemple 1, on a utilisé comme précurseur Ba2Ca2Cu3Ox et une proportion de précuseur a été mélangée à deux proportions d'AgO et à une proportion de CuO.Under the same pressure and temperature conditions as in Example 1, Ba 2 Ca 2 Cu 3 O x was used as precursor and a proportion of precusor was mixed with two proportions of AgO and one proportion of CuO.

La courbe de susceptibilité magnétique en fonction de la température est indiquée en figure 2. On aperçoit une transition supraconductrice pour une température de 77 K, la phase du composé supraconducteur ayant été identifiée comme la phase pour laquelle n=3. The magnetic susceptibility curve as a function of the temperature is indicated in figure 2. We see a transition superconductive for a temperature of 77 K, the phase of superconductive compound having been identified as the phase for which n = 3.

Exemple 3Example 3

Dans les mêmes conditions de pression et de température que dans l'exemple 1, on a utilisé comme précurseur Ba2Ca2Cu3Ox qui a été mélangé à une proportion de Ag2O.Under the same pressure and temperature conditions as in Example 1, Ba 2 Ca 2 Cu 3 O x was used as a precursor which was mixed with a proportion of Ag 2 O.

La courbe de susceptibilité magnétique en fonction de la température est donnée par la figure 3. On voit que la transition supraconductrice apparait pour une température de 120 K. Dans l'état actuel des mesures, on suppose que ce composé correspond à la phase n=4 ou 5.The magnetic susceptibility curve as a function of the temperature is given by figure 3. We see that the transition superconductive appears for a temperature of 120 K. In the current state of the measurements, it is assumed that this compound corresponds in phase n = 4 or 5.

Exemple 4Example 4

Dans les mêmes conditions de pression et de température que dans l'exemple 1, on a utilisé comme précurseur Ba2Ca2Cu4Ox qui a été mélangé à deux proportions d'AgO.Under the same pressure and temperature conditions as in Example 1, Ba 2 Ca 2 Cu 4 O x was used as precursor which was mixed with two proportions of AgO.

La courbe de susceptibilité magnétique, illustrée en figure 4 présente comme celle de la figure 3 une transition marquée à 120 K. Néanmoins, en considérant à échelle beaucoup plus agrandie cette susceptibilité magnétique, on note qu'un décrochement apparaít à une température de 275 K, c'est-à-dire +2°C. Des expériences similaires à haute sensibilité n'ont pas été effectuées pour les échantillons des figures 1, 2 et 3 et il n'est pas exclu que des résultats similaires apparaissent aussi pour ces échantillons.The magnetic susceptibility curve, illustrated in figure 4 presents like that of figure 3 a transition marked at 120 K. Nevertheless, considering on a large scale more magnified this magnetic susceptibility, we note that a setback appears at a temperature of 275 K, that is to say + 2 ° C. Similar high-sensitivity experiments did not were performed for the samples in Figures 1, 2 and 3 and it it is not excluded that similar results also appear for these samples.

La phase à laquelle correspond le matériau présentant cette température critique très élevée n'a pas été identifiée avec précision mais on considère aujourd'hui qu'il s'agit d'un matériau pour lequel la phase n est élevée (de l'ordre de 6 ou plus). D'autre part, cette valeur élevée de la température critique peut être due au maintien d'atomes d'argent à l'intérieur de la phase supraconductrice.The phase to which the material exhibiting corresponds this very high critical temperature has not been identified with precision but today we consider that it is a material for which the phase n is high (of the order of 6 or more). On the other hand, this high value of the critical temperature may be due to the keeping of silver atoms inside of the superconducting phase.

Ainsi, le procédé selon la présente invention permet d'obtenir un composé supraconducteur dont la formule principale est CuBa2Can-1CunOx mais plus généralement, la présente invention vise tout corps obtenu par le procédé décrit consistant à fabriquer une céramique sous haute pression et haute température à partir d'un précurseur ou d'un mélange de précurseurs de Ba2Can-1Cun+1Ox en présence d'argent pour fournir un matériau supraconducteur à température critique élevée. Ce composé peut comprendre un excès de calcium et un défaut de baryum selon la formule CuBa2-yCan-1+yCunOx où y est compris entre 0 et 0,5.Thus, the method according to the present invention makes it possible to obtain a superconductive compound whose main formula is CuBa 2 Ca n-1 Cu n O x but more generally, the present invention relates to any body obtained by the described method consisting in manufacturing a ceramic under high pressure and high temperature from a precursor or a mixture of precursors of Ba 2 Ca n-1 Cu n + 1 O x in the presence of silver to provide a superconductive material at high critical temperature. This compound can comprise an excess of calcium and a barium defect according to the formula CuBa 2-y Ca n-1 + y Cu n O x where y is between 0 and 0.5.

On notera que la composition du précurseur peut être modifiée et n'est pas nécessairement strictement stoechiométrique. De même, on pourra prévoir des quantités variables d'oxyde d'argent, couramment dans une plage d'une à trois moles d'oxyde d'argent pour une mole de précurseur.Note that the composition of the precursor can be modified and is not necessarily strictly stoichiometric. Likewise, variable amounts of oxide may be provided silver, commonly in the range of one to three moles of oxide money for one mole of precursor.

Claims (9)

  1. A method of preparing a superconductor material characterized in that it comprises the following steps:
    preparing a precursors constituted by a powder of Ba2Can-1Cun+1Ox or Ba2Can-1CunOx where n is an integer greater than 1 and x is greater than 2n+2;
    mixing said powder with silver oxide power, optionally in the presence of excess copper oxide, in a proportion of one mole of precursor for one to three moles of silver oxide; and
    heating to high temperature and high pressure.
  2. A method of preparation according to claim 1, characterized in that the precursor is made up from oxidized compounds such as the oxide, nitrate, or carbonate of barium, calcium, or copper in the specified proportions, and heated under oxygen at atmospheric pressure for several hours.
  3. A method according to claim 1, characterized in that the silver oxide is of the AgO or the Ag2O type.
  4. A method according to claim 1, characterized in that the step of heating to high temperature and high pressure is performed at a pressure greater than about 4 GPa and at a temperature greater than 850°C.
  5. A method according to claim 4, characterized in that said temperature is less than 1000°C.
  6. A method according to claim 4, characterized in that said temperature is close to 900°C.
  7. A superconductor material of the ABa2Can-1CunOx type where n is an integer greater than 1 and where x is greater than 2n+2, characterized in that A is copper and in that the material includes traces of silver.
  8. A superconductor material according to claim 7, characterized in that n is greater than or equal to 3.
  9. A superconductor material according to claim 7, characterized in that it includes excess calcium and a deficit of barium in application of the formula CuBa2-yCan-1+yCunOx where y lies in the range 0 to 0.5.
EP95907684A 1994-01-26 1995-01-19 Superconducting material and method for preparing superconducting materials Expired - Lifetime EP0741678B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9401097A FR2715397B1 (en) 1994-01-26 1994-01-26 Superconductive material and process for preparing superconductive materials.
FR9401097 1994-01-26
PCT/FR1995/000059 WO1995020550A1 (en) 1994-01-26 1995-01-19 Superconducting material and method for preparing superconducting materials

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US7674759B2 (en) 2007-09-05 2010-03-09 Conopco, Inc. Stable liquid cleansing compositions containing high level of fatty acid isethionate surfactant products having more than 10 wt. % of fatty acid/fatty soap content
US7807612B2 (en) 2007-12-18 2010-10-05 Conopco, Inc. Fatty acyl isethionate product-containing liquid cleansing compositions stabilized with mixture of long chain and short chain fatty acids/fatty soaps
US7879780B2 (en) 2008-09-23 2011-02-01 Conopco, Inc. Stable cleansing compositions containing fatty acyl isethionate surfactant products having more than 10 wt. % of fatty acid/fatty soap content using high level of polyol and methods thereof

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EP0660424A2 (en) * 1993-12-24 1995-06-28 International Superconductivity Technology Center Oxide superconductor and method of producing same

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EP0660424A2 (en) * 1993-12-24 1995-06-28 International Superconductivity Technology Center Oxide superconductor and method of producing same

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US5952268A (en) 1999-09-14
WO1995020550A1 (en) 1995-08-03
CA2181601A1 (en) 1995-08-03
EP0741678A1 (en) 1996-11-13
JPH09508344A (en) 1997-08-26
CA2181601C (en) 2001-03-20
ES2133731T3 (en) 1999-09-16
DE69509749D1 (en) 1999-06-24
FR2715397A1 (en) 1995-07-28
FR2715397B1 (en) 1996-03-15
DE69509749T2 (en) 1999-12-23

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